Meaning of “light (sth) up” - Learner’s Dictionary

light (sth) up

phrasal verb with light us uk /laɪt/ verb past tense and past participle lit, lighted

to make a cigarette, etc start burning:

He made himself a coffee and lit up / a cigarette.

(Definition of “light (sth) up” from the Cambridge Learner’s Dictionary © Cambridge University Press)